Method for Forming Insulation Film

ABSTRACT

In a process involving the formation of an insulating film on a substrate for an electronic device, the insulating film is formed on the substrate surface by carrying out two or more steps for regulating the characteristic of the insulating film involved in the process under the same operation principle. The formation of an insulating film having a high level of cleanness can be realized by carrying out treatment such as cleaning, oxidation, nitriding, and a film thickness reduction while avoiding exposure to the air. Further, carrying out various steps regarding the formation of an insulating film under the same operation principle can realize simplification of the form of an apparatus and can form an insulating film having excellent property with a high efficiency.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 12/145,971, filed Jun. 25, 2008, which is a continuation applicationof U.S. application Ser. No. 10/509,370, filed Sep. 28, 2004, which is aNational Phase of PCT/JP2003/004091, filed Mar. 31, 2003 and whichclaims priority under 35 U.S.C. §119 to Japanese Patent Application No.2002-097906, filed Mar. 29, 2002, the entire disclosures of which areherein expressly incorporated by reference.

TECHNICAL FIELD

The present invention relates to a process for forming an insulatingfilm having various excellent characteristics (for example, control ofvery small film thickness and a high level of cleanness) with a highefficiency (for example, small footprint provided by conducting varioussteps in a single reaction chamber, or simplification of operationalityand prevention of cross-contamination between apparatuses realized byconducting various steps in separate reaction chambers under the sameprinciple of operation). The process for forming an electronic devicematerial according to the present invention is suitably usable for theformation of a material, for example, for a semiconductor or asemiconductor device (for example, one having an MOS-type semiconductorstructure with a gate insulating film having an excellentcharacteristic).

BACKGROUND ART

The present invention is generally and widely applicable to theformation of electronic device materials, for example, forsemiconductors or semiconductor devices and liquid crystal devices.Herein, for the convenience of explanation, the background art relatingto semiconductor devices will be explained as an example.

Substrates for semiconductor. or electronic device materials includingsilicon are subjected to various types of treatment such as formation ofinsulating films including oxide films, formation of films by CVD or thelike, and etching.

It is not too much to say that an improvement in the performance ofsemiconductor devices in recent years has been achieved by virtue oftechniques for microfabrication of the devices including transistors.Even today, an effort is still being made to further improve thetransistor microfabrication techniques for higher performance. A demandfor a higher level of microfabrication and higher performance ofsemiconductor devices in recent years has led to ever-increasing needsfor insulating films with higher performance, for example, in terms ofleakage current. The reason for this is that, in recent microfabricated,highly integrated and/or higher-performance devices, even a low level ofleakage current may possibly cause severe problems, although such aleakage current does not pose substantially no problem in the case ofconventional relatively low-integrated devices. In particular, low-powerconsumption devices are indispensable to the development of portableelectronic devices in the so-called ubiquitous society(information-oriented society using as a medium electronic devices whichcan be connected to networks anywhere at any time) which has begun inrecent years, and, to this end, a reduction in leakage current is veryimportant.

Typically, for example, in the development of a next-generation oradvanced MOS transistor, with the advancement of the abovemicrofabrication technique, the possible thickness reduction of gateinsulating films has approached to its limit, and, consequently, asevere problem to be overcome has appeared. More specifically, accordingto process technology, the thickness of a silicon oxide (SiO₂) film,which is currently used as a gate insulating film, can be reduced to themaximum (level of 1 to 2 atomic layers). However, when the filmthickness is reduced to 2 nm or less, the leakage current due to adirect tunnel by quantum effect is increased exponentially, so as toincreased the power consumption disadvantageously.

At the present time, IT (information technology) markets are beingtransformed from stationary electronic devices typified, for example, bydesktop personal computers and home telephones (devices in whichelectric power is supplied from a receptacle) to “ubiquitous networksociety” in which electronic devices are accessible to the Internet andthe like anywhere at any time. Therefore, in the very near future,portable terminals such as portable telephones (cellular phones) and carnavigation systems are considered to be mainly used. Such portableterminals per se are required to be a high performance device. At thesame time, requirements for small size, lightweight, and functionscapable of withstanding use for a long period of time should besatisfied, although such requirements are not very important to theabove stationary devices. Therefore, in portable terminals, reducingpower consumption while improving performance is very important.

Typically, for example, in the development of next-generation MOStransistors, enhancing the level of microfabrication of high-performancesilicon LSI poses problems of increased leakage current and increasedpower consumption. In order to reduce the power consumption whileenhancing the performance, the characteristics of MOS transistors shouldbe improved without increasing gate leakage current in the transistors.

The formation of a good-quality and thin (for example, a film thicknessof not more than about 15 A (angstroms)) insulating film isindispensable for simultaneously achieving an enhancement in the levelof microfabrication and an improvement in characteristics.

However, the formation of a good-quality and thin insulating film isvery difficult. For example, an insulating film formed by conventionalthermal oxidation or CVD (chemical vapor deposition method) isunsatisfactory in any one of characteristics, i.e., either film qualityor film thickness.

DISCLOSURE OF INVENTION

An object of the present invention is to solve the drawbacks encounteredin the prior art and to provide a process for forming a thin insulatingfilm on a substrate for an electronic device.

Another object of the present invention is to provide a process forforming a thin insulating film on the surface of a substrate for anelectronic device, which can suitably carry out post-treatment (forexample, formation of films by CVD or the like and etching) and canprovide an insulating film excellent in both film quality and filmthickness.

A further object of the present invention is to carry out various stepsinvolved in the formation of an insulating film under the same principleof operation, thereby simplifying the apparatus form and efficientlyforming an insulating film having an excellent characteristic. As aresult of earnest study, the present inventors have found that theformation of an insulating film by a method which enables not only thepractice of one step in one apparatus as in the prior art but also thepractice of various steps in a single apparatus is very effective forattaining the above objects.

The process or forming an insulating film formation on the surface of asubstrate for an electronic device according to the present invention isbased on the above discovery. More specifically the process comprises:at least two steps of regulating the characteristic-of the insulatingfilm, wherein the at least two steps of regulating the characteristic ofthe insulating film are conducted under the same operation principle.For example, the present invention may include some embodiments whereinthe application of plasma to a substrate for an electronic device usinga process gas comprising at least a rare gas can provide a cleaningeffect, the incorporation of oxygen or nitrogen in the same plasmacauses oxidation or nitridation, or the application of the same plasmacontaining at least hydrogen to an oxygen atom-containing insulatingfilm including an oxide film can reduce the thickness of the insulatingfilm.

In the process for forming an insulating film according to the presentinvention having the above constitution, for example, an insulating filmhaving any desired thickness can easily be formed by forming a filmhaving a desired thickness with attention focused on film quality andthen reducing the film thickness by a specific plasma treatment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing one embodiment of an MOSstructure which can be formed according to the present invention.

FIG. 2 is a partial schematic sectional view showing one embodiment of asemiconductor production device usable in the process for forming aninsulating film according to the present invention.

FIG. 3 is a schematic vertical sectional view showing one embodiment ofa plane antenna member (RLSA; also referred to as slot plane antenna orSPA) plasma processing unit usable in the process for forming aninsulating film according to the present invention.

FIG. 4 is a schematic plan view showing one embodiment of RLSA usable ina apparatus for producing an electronic device material according to thepresent invention.

FIG. 5 is a graph showing a leakage characteristic of an oxide film in acase where the oxide film has been subjected to a pre-oxidation plasmatreatment, and the oxide film has not been subjected to a pre-oxidationplasma treatment. In this figure, the abscissa denotes the electricalfilm thickness and the ordinate denotes the leakage current value forthe gate oxide film at a gate voltage Vfb −0.4 V.

FIG. 6 is a diagram showing a flatband characteristic of a similar film.In this figure, the abscissa denotes the electrical film thickness andthe ordinate denotes the flatband voltage.

FIG. 7 a is a diagram showing a change in the electrical film thicknessof a gate oxynitride film using a plurality of steps (multi-process) inthe present invention with the elapse of time (i.e., a change in theelectrical film thickness in each step). In this figure, the abscissadenotes the treatment time, and the ordinate denotes the electrical filmthickness.

FIG. 7 b is a diagram showing a change in the electrical film thicknessof a film similar to that of FIG. 6 with the elapse of time (i.e., achange in the electrical film thickness in each step). In this figure,the abscissa denotes the treatment time, and the ordinate denotes theelectrical film thickness.

FIG. 8 is a diagram showing the results of SIMS analysis for theconcentration of oxygen in a film similar to that of FIG. 6, In thisfigure, the abscissa denotes the etching time in the analysis, and theordinate denotes the oxygen signal intensity.

FIG. 9 is a schematic sectional view showing one embodiment of thesurface of a silicon substrate on which a gate oxide film and a gateinsulating film are to be formed.

FIG. 10 is a schematic sectional view showing one embodiment of plasmatreatment to be effected on the surface of a substrate.

FIG. 11 is a schematic sectional view showing one embodiment of theformation of an SiO₂ film on a substrate using plasma, nitriding, andhydrogen plasma treatment.

FIG. 12 is a schematic sectional view showing one embodiment of theformation of a film using a Hi-k material.

FIG. 13 is a schematic sectional view showing one embodiment of theformation of a gate electrode on a Hi-k material film.

FIG. 14 is a schematic sectional view showing one embodiment of theformation of an MOS capacitor.

FIG. 15 is a schematic sectional view showing one embodiment of theformation of a source and a drain by ion implantation.

FIG. 16 is a schematic sectional view showing one embodiment of an MOStransistor structure provided by the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in detail withreference to the accompanying drawings as desired. In the followingdescription, “%” and “part(s)” representing a quantitative proportion orratio are those based on mass, unless otherwise specifically noted.

(Process for Forming Insulating Film)

In the present invention, a very thin (not more than 15 A) insulatingfilm can be formed by adopting a desired combination of two or moresteps, e.g., a step of applying plasma to a substrate for an electronicdevice using a process gas comprising at least a rare gas to attain acleaning effect, a step of incorporating oxygen or nitrogen in the sameplasma for oxidation or nitridation, and a step of applying the sameplasma containing at least hydrogen to an oxygen atom-containinginsulating film including an oxide film to reduce the thickness of theinsulating film. The process for forming an insulating film according tothe present invention can be applied to any object without particularlimitation. For example, the present invention can provide a thininsulating film having a surface particularly suitable for the formationof a film of a high-dielectric constant (high-k) material sensitive tothe film-forming conditions and the like.

(Insulating Film to be Formed)

The composition, thickness, production process, and properties of aninsulating film formable by the present invention are as follows.Composition: oxide film, oxynitride film, and nitride filmProduction process: a process in which, in a single vessel using plasmacomprising at least a rare gas, one or at least two of a step ofcleaning, a step of oxidation, a step of nitriding, and a step of filmthickness reduction is carried out on an electronic substrate; or aprocess in which plasma comprising at least a rare gas is producedwithin a plurality of vessels under the same principle of operation anda step of cleaning, a step of oxidation, a step of nitriding, or a stepof film thick reduction is carried out on an electronic substrate.Thickness: physical thin film 5 A to 20 A

(Evaluation of Film Quality and Film Thickness)

The level of the film quality and the level of the film thickness of thethin insulating film, which has been formed according to the presentinvention, can be suitably evaluated, for example, by actually forming afilm of a high-k material on the surface of the thin film. In this case,whether or not a high-quality high-k material film has been formed canbe evaluated, by a method wherein a standard MOS semiconductor structureas described in a publication (see, Masanori Kishino and MitsumasaKoyanagi, “VLSI Device no Butsuri (Physics of VLSI Devices)”, pp. 62-63,published by Maruzen) is fabricated and the evaluation of thecharacteristic of the thus fabricated MOS can be used as the evaluationof the characteristic of the insulating film itself. This is because, insuch a standard MOS structure, the characteristic of the insulating filmconstituting the MOS structure has much effect on the MOScharacteristic.

Regarding the formation of this MOS structure, for example, an MOScapacitor comprising a high-k material film can be formed underconditions of Example 1 appearing hereinafter. In the formation of anMOS capacitor comprising a high-k material film under conditions ofExample 1, according to the present invention, it is preferred that (1)flatband characteristic or (2) leak characteristic (more preferably,both of these) as described below are provided.

(1) Preferred flatband characteristic: Within ±50 mV as compared withthermally grown oxide film

(2) Leak characteristic: Reduction by one figure (or digit) as comparedwith thermally grown oxide film, or less

(Combination with Post-Treatment)

A thin insulating film formed by the process for forming an insulatingfilm according to the present invention is suitable for the subsequentvarious types of treatment. The “post-treatment” is not particularlylimited and may be various types of treatment such as formation of anoxide film, formation of film by CVD or the like, and etching. Theprocess for forming an insulating film according to the presentinvention can be carried out at a low temperature. Therefore, regardingthe subsequent treatment as well, a combination with treatment underrelatively low (preferably 600° C. or below, more preferably 500° C. orbelow) temperature conditions is particularly effective. The reason forthis is that, since the use of the present invention enables theformation of an oxide film, i.e., one of the steps requiring the highesttemperature in the device preparation process, to be carried out at alow temperature, a device can be prepared while avoiding ahigh-temperature heat history.

(Substrate for Electronic Device)

The substrate for an electronic device usable in the present inventionis not particularly limited, and one or a combination of two or more ofconventional substrates for an electronic device may be properlyselected and used. Examples of such substrates for an electronic devicemay include semiconductor materials and liquid crystal device materials.Examples of semiconductor materials may include materials mainlycomprising single-crystal silicon and materials mainly comprisingsilicon germanium.

(Process Gas)

Any process gas may be used in the present invention without particularlimitation, as long as the gas contains at least a rare gas, and one ora combination of two or more of conventional process gases usable in the

production of electronic devices may be properly selected and used.Examples of such process gases (rare gas) may include: Ar (argon), He(helium), Kr (krypton), Xe (xenon), Ne (neon), O₂ (oxygen), N₂(nitrogen), H₂ (hydrogen), and NH₃ (ammonia).

(Treatment Conditions)

In the formation of an insulating film according to the presentinvention, the following conditions are suitably usable from theviewpoint of the property of the thin insulating film to be formed.

Rare gas (for example, Kr, Ar, He, Xe, or Ne): 500 to 3000 sccm, morepreferably 1000 to 2000 sccm.

In a step of cleaning, a process gas comprising at least a rare gas maybe used, and a hydrogen gas may further be added. The flow rate of thehydrogen gas H₂ may be 0 to 100 sccm, more preferably 0 to 50 sccm. In astep of oxidation, a process gas comprising at least a rare gas andoxygen may be used, and the flow rate of the oxygen gas O₂ may be 10 to500 sccm, more preferably 10 to 200 sccm.

In a step of nitriding, a process gas comprising at least a rare gas andnitrogen may be used, and the flow rate of the nitrogen gas N₂ may be 3to 300 sccm, more preferably 20 to 200 sccm.

In a step of etching, a process gas comprising at least a rare gas andhydrogen may be used, and the flow rate of the hydrogen gas H₂ is 0 to100 sccm, more 5 preferably 0 to 50 sccm.

Temperature: room temperature 25° C. to 500° C., more preferably 250 to500° C., particularly preferably 250 to 400° C.

Pressure: 3 to 500 Pa, more preferably 7 to 260 Pa

Microwave: 1 to 5 W/cm², more preferably 2 to 4 W/cm², particularlypreferably 2 to 3 W/cm²

In the present invention, any plasma may be used without particularlimitation. It is preferred to use plasma with a relatively low electrontemperature and a high density, from the viewpoint of easiness onuniform film thickness reduction.

(Suitable Plasma)

The property of plasma which is suitably used in the present inventionis as follows.

Electron temperature: 0.5 to 2.0 eV

Density: 1E10 to 5E12/cm³

Uniformity of plasma density: ±10%

(Plane Antenna Member)

In the process for forming an insulating film according to the presentinvention, it is preferred that plasma with a low electron temperatureand a high density is formed by the application of microwaves through aplane antenna member provided with a plurality of slots. In the presentinvention, since an oxynitride film is formed using plasma having suchan excellent property, a low-plasma damage, low-temperature, and highlyreactive process can be realized. Further, in the present invention, ascompared with the use of conventional plasma, the application ofmicrowaves through the plane antenna member is advantageous in that aninsulating film, the thickness of which has been more suitably reducedcan easily be formed.

According to the present invention, an insulating film with a reducedfilm thickness can be formed. Therefore, a semiconductor devicestructure having an excellent characteristic can easily be formed byforming another layer (for example, another insulating layer) on theinsulating film with a reduced film thickness. The insulating film witha thickness reduced by the present invention is particularly suitablefor the formation of a high-k material film on the surface of theinsulating film with a reduced film thickness.

(High-k Material)

The high-k material usable in the present invention is not particularlylimited. The value of the k (specific dielectric constant) maypreferably be not less than 7, more preferably, not less than 10, fromthe viewpoint of increasing the physical film thickness.

Preferred examples of the high-k material may be one or at least twohigh-k materials selected from the group consisting of: A1₂O₃r ZrO₂,HfO₂, Ta₂O₅, and silicates such as ZrSiO, HfSiO; aluminates such asZrAlO.

(Treatment in the Same Vessel)

The expression “in the same vessel” which will be described below meansthat, after a certain step, the substrate to be treated is subjected toa subsequent treatment without passage through the wall of the vessel.In the case of the use of the so-called “cluster” structure using acombination of a plurality of vessels, when the transfer of thesubstrate between different vessels constituting the cluster is carriedout, this treatment is not treatment “in the same vessel” referred to inthe present invention.

In this way, in the present invention, “in the same vessel” without theexposure of the substrate to be formed (such as a silicon substrate) tothe air, a plurality of steps can be successively carried out in areaction chamber under the same principle. For example, a reduction infootprint can be realized by conducting all steps in a single reactionchamber. Further, also when the individual steps are carried out inrespective separate reaction chambers, since reaction chambers identicalto each other in the principle of operation are arranged, the same gaspiping and operation panel can be used, to thereby realize an excellentmaintenance and operationality. Further, the same apparatus is used,there is no significant fear of cross-contamination between theapparatuses. Even when a cluster construction using a plurality ofreaction chambers is adopted, the processing order can be changed invarious ways. A gate insulating film having various characteristics canbe prepared by this method.

The oxide film or oxynitride film formed according to the presentinvention as such may be used as a gate insulating film. Alternatively,a process may be adopted which comprises forming a very thin (about 10 A(angstroms)) oxide film or oxynitride film according to the presentinvention and forming thereon a film of a material a having highdielectric constant such as a high-k material. According to this method,a stacked gate insulating film structure (gate stack structure) having ahigher level of interfacial characteristic (such as a higher level oftransistor carrier mobility) than the gate insulating film formed usinga high-k material only.

(Suitable Characteristic of MOS Semiconductor Structure)

The very thin and good-quality insulating film formable on the substratecleaned by the present invention is particularly suitable for theutilization as an insulating film in a semiconductor device(particularly, a gate insulating film in an MOS semiconductorstructure).

According to the present invention, as described below, an MOSsemiconductor structure having suitable characteristic can easily beproduced. The characteristic of the oxynitride film formed by thepresent invention can be evaluated, by a method wherein a standard MOSsemiconductor structure as described in a publication (see, MasanoriKishino and Mitsumasa Koyanagi, “Physics of VLSI Devices”, pp. 62-63,published by Maruzen) is fabricated and the evaluation of thecharacteristic of the thus fabricated MOS can be used as the evaluationof the characteristic of the oxynitride film itself. This is because, insuch a standard MOS structure, the characteristic of the oxynitride filmconstituting the MOS structure has much effect on the MOScharacteristic.

(One Embodiment of Production Apparatus)

A preferred embodiment of the production process according to thepresent invention will be described.

At the outset, regarding one embodiment of the structure of asemiconductor device which can be produced by the production process ofan electronic device material according to the present invention, asemiconductor device having an MOS structure provided with a gateinsulating film as an insulating film will be described with referenceto FIG. 1.

In FIG. 1 (a), reference numeral 1 designates a silicon substrate,numeral 11 a field oxide film, numeral 2 a gate insulating film, andnumeral 13 a gate electrode. As described above, in the productionprocess according to the present invention, a very thin and good-qualitygate insulating film 2 can be formed. As shown in FIG. 1 (b), this gateinsulating film 2 comprises a high-quality insulating film formed at theinterface of the silicon substrate 1. For example, the gate insulatingfilm 2 comprises an about 2 nm-thick oxide film or oxynitride film.

In this embodiment, it is preferred that this high-quality oxide film 2comprises a silicon oxynitride film (hereinafter referred to as “SiONfilm”) formed using plasma produced on the surface of an objectsubstrate mainly comprising silicon (Si) by applying microwave through aplane antenna member provided with a plurality of slots to the substratein the presence of a process gas containing O₂, N₂ and rare gas. Whenthis SiON 2 film is used, as described below, advantageously, theinterphase interfacial quality (for example, interfacial level) is good,and, in the form of an MOS structure, good gate leak characteristic caneasily be provided. In the embodiment shown in FIG. 1, a gate electrode13 mainly comprising silicon (polysilicon or amorphous silicon) isfurther provided on the surface of the silicon oxynitride film.

(One Embodiment of Production Process)

A process for forming of the above silicon oxynitride film will bedescribed.

FIG. 2 is schematic view (schematic plan view) showing an example of thetotal arrangement of a semiconductor manufacturing equipment 30 forconducting the process for producing an electronic device materialaccording to the present invention.

As shown in FIG. 2, in a substantially central portion of thesemiconductor manufacturing equipment 30, there is disposed atransportation chamber 31 for transporting a wafer W (FIG. 3). Aroundthe transportation chamber 31, there are disposed: plasma processingunits 32 and 33 for conducting various treatments on the wafer, two loadlock units 34 and 35 for conducting the communication/cutoff between therespective processing chambers, a heating unit 36 for operating variousheating treatments, and a heating reaction furnace 47 for conductingvarious heating treatments on the wafer. These units are disposed so asto surround the transportation chamber 31.

On the side of the load lock units 34 and 35, a preliminary cooling unit45 and a cooling unit 46 for conducting various kinds of preliminarycooling and cooling treatments are disposed.

In the inside of transportation chamber 31, transportation arms 37 and38 are disposed, so as to transport the wafer W (FIG. 2) between theabove-mentioned respective units 32-36.

On the foreground side of the load lock units 34 and 35 in this figure,loader arms 41 and 42 are disposed. These loader arms 41 and 42 can putwafer W in and out with respect to four cassettes 44 which are set onthe cassette stage 43, which is disposed on the foreground side of theloader arms 41 and 42.

In FIG. 2, as the plasma processing units 32 and 33, two plasmaprocessing units of the same type are disposed in parallel.

Further, it is possible to exchange both of the plasma processing units32 and 33 with a single-chamber type CVD process unit. It is possible toset one or two of such a single-chamber type CVD process unit in theposition of the plasma processing units 32 and 33.

When two plasma processing units 32 and 33 are used, it is possible thatan SiO₂ film is formed in the plasma processing unit 32, and then theSiO₂ film is subjected to surface nitridation in the plasma processingunit 33. Alternatively, it is also possible an SiO₂ film is formed, andthe SiO₂ film is surface-nitrided in parallel, in the plasma processingunits 32 and 33.

(One Embodiment of Plasma Processing Apparatus)

FIG. 3 is a schematic sectional view in the vertical direction showingthe plasma processing unit 32 (or 33) which is usable in the filmformation of the gate insulator 2.

Referring to FIG. 3, reference numeral 50 denotes a vacuum containermade of, e.g., aluminum. In the upper portion of the vacuum container50, an opening portion 51 is formed so that the opening portion 51 islarger than a substrate (for example, wafer W). A top plate 54 in a flatcylindrical shape made of a dielectric such as quartz and aluminum oxideso as to cover the opening portion 51. In the side wall of the upperportion of vacuum container 50 which is below the top plate 54, gas feedpipes 72 are disposed in the 16 positions, which are arranged along thecircumferential direction so as to provide equal intervals therebetween.A process gas comprising at least one kind of gas selected from O₂,inert gas, N₂, H₂, etc., can be supplied into the vicinity of the plasmaregion P in the vacuum container 50 from the gas feed pipes 72 evenlyand uniformly.

On the outside of the top plate 54, there is provided a radio-frequencypower source, via a plane antenna member 60 having a plurality of slots,which comprises a plane antenna (RLSA) made from a copper plate, forexample. As the radio-frequency power source, a waveguide 63 is disposedon the top plate 54, and the waveguide 63 is connected to a microwavepower supply 61 for generating microwave of 2.45 GHz, for example. Thewaveguide 63 comprises a combination of: a flat circular waveguide 63A,of which lower end is connected to the RLSA 60; a circular waveguide63B, one end of which is connected to the upper surface side of thecircular waveguide 63A; a coaxial waveguide converter 63C connected tothe upper surface side of the circular waveguide 63B; and a rectangularwaveguide 63D, one end of which is connected to the side surface of thecoaxial waveguide converter 63C so as to provide a right angletherebetween, and the other end of which is connected to the microwavepower supply 61.

In the inside of the above-mentioned circular waveguide 63B, an axialportion 62 of an electroconductive material is coaxially provided, sothat one end of the axial portion 62 is connected to the central (ornearly central) portion of the RLSA 60 upper surface, and the other endof the axial portion 62 is connected to the upper surface of thecircular waveguide 63B, whereby the circular waveguide 63B constitutes acoaxial structure. As a result, the circular waveguide 63B isconstituted so as to function as a coaxial waveguide.

In addition, in the vacuum container 50, a stage 52 for carrying thewafer W is provided so that the stage 52 is disposed opposite to the topplate 54. The stage 52 contains a temperature control unit (not shown)disposed therein, so that the stage can function as a hot plate.Further, one end of an exhaust pipe 53 is connected to the bottomportion of the vacuum container 50, and the other end of the exhaustpipe 53 is connected to a vacuum pump 55.

(One Embodiment of RLSA)

FIG. 4 is a schematic plan view showing an example of RLSA 60 which isusable in an apparatus for producing an electronic device materialaccording to the present invention.

As shown in this FIG. 4, on the surface of the RLSA 60, a plurality ofslots 60 a, 60 a, . . . are provided in the form of concentric circles.Each slot 60 a is a substantially square penetration-type groove. Theadjacent slots are disposed perpendicularly to each other and arrangedso as to form a shape of alphabetical “T”-type character. The length andthe interval of the slot 60 a arrangement are determined in accordancewith the wavelength of the microwave supplied from the microwave powersupply unit 61.

(Embodiment of Plasma Processing)

Next, there is described an embodiment of the process processing to beused in the present invention.

A gate valve (not shown) provided at the side wall of the vacuumcontainer 50 in the plasma processing unit 32 (FIG. 2) is opened, andthe above-mentioned wafer W comprising the silicon substrate 1, and thefield oxide film 11 formed on the surface of the silicon substrate 1 isplaced on the stage 52 (FIG. 3) by means of transportation arms 37 and38.

Next, the gate valve was closed so as to seal the inside of the vacuumcontainer 50, and then the inner atmosphere therein is exhausted by thevacuum pump 55 through the exhaust pipe 53 so as to evacuate the vacuumcontainer 50 to a predetermined degree of vacuum and a predeterminedpressure in the container 50 is maintained. On the other hand, microwave(e.g., of 1.80 GHz and 2200 W) is generated by the microwave powersupply 61, and the microwave is guided by the waveguide so that themicrowave is introduced into the vacuum container 50 via the RLSA 60 andthe top plate 54, whereby radio-frequency plasma is generated in theplasma region P of an upper portion in the vacuum container 50.

Herein, the microwave is transmitted in the rectangular waveguide 63D ina rectangular mode, and is converted from the rectangular mode into acircular mode by the coaxial waveguide converter 63C. The microwave isthen transmitted in the cylindrical coaxial waveguide 63B in thecircular mode, and transmitted in the circular waveguide 63A in theexpanded state, and is emitted from the slots 60 a of the RLSA 60, andpenetrates the plate 54 and is introduced into the vacuum container 50.In this case, microwave is used, and accordingly a high-density andlow-electron temperature plasma can be generated. Further, the microwaveis emitted from a large number of slots 60 a of the RLSA 60, andaccordingly the plasma is caused to have a uniform distribution.

When an oxide film is formed, the wafer W is introduced into thereaction chamber 50 (FIG. 3) prior to the induction of microwave, and aprocess gas comprising a rare gas (such as krypton and argon) and oxygengas as a gas for forming an oxide film, is introduced at flow rates of2000 sccm and 200 sccm, respectively, into the reaction chamber from thegas feed pipe 52, while heating the wafer with the stage 52. Thepressure of the reaction chamber is maintained at 133 Pa and microwaveis introduced thereinto at 2 W/cm² so as to generate plasma, and oxygenradicals are caused to react on the substrate W surface, to thereby forma silicon oxide film. In the case of pre-oxidation treatment, it ispreferred to use a rare gas only, or a rare gas and hydrogen gas as theprocess gas. In the case of nitridation treatment, it is preferred touse a rare gas and nitrogen-containing gas as the process gas.

Hereinbelow, the present invention will be described in more detail withreference to Examples.

EXAMPLES Example 1

A device (N-type MOS capacitor) for carrying out various evaluations wasformed by the following method.

(1): Substrate (FIG. 9)

As shown in FIG. 9, a P-type silicon substrate having a specificresistance of 8 to 12 Ωcm and plane orientation (100) was used as asubstrate. The surface of the silicon substrate had a sacrificial oxidefilm with a thickness of 500 A (angstrom) previously formed by thermaloxidation.

(2): Cleaning Before Gate Oxidation

The sacrificial oxide film and contamination elements (metals andorganic matter, particles) were removed by RCA cleaning using acombination of APM (a mixed liquid composed of ammonia, aqueous hydrogenperoxide, and pure water) with HPM (a mixed liquid composed ofhydrochloric acid, aqueous hydrogen peroxide, and pure water) and DHF (amixed liquid composed of hydrofluoric acid and pure water).

(3): Plasma Treatment Before Oxidation (FIG. 10)

After the treatment in the above step (2), RLSA plasma treatment wascarried out on the substrate (FIG. 10) under the following conditions. Awafer was transferred to a reaction chamber indicated by 32 in FIG. 2and FIG. 3 under vacuum (back pressure: not more than 1×10⁻⁴ Pa), andthe conditions were then held in the following manner: substratetemperature of 400° C., rare gas (for example, Ar gas) of 1000 sccm, andpressure of 7 Pa to 133 Pa (50 mTorr to 1 Torr). A microwave was appliedat 2 to 3 W/cm² to this atmosphere through a plane antenna member (RLSA)having a plurality of slots to generate rare gas plasma for plasmatreatment on the substrate surface (FIG. 10). As desired, hydrogen (5 to30 sccm) may be contained in the rare gas for hydrogen pre-oxidationplasma treatment.

(4): Plasma Oxidation Process (FIG. 11)

An oxide film was formed by the following method on the siliconsubstrate treated in the step (3). While avoiding the exposure of thesilicon substrate treated in the step (3) to the air, the siliconsubstrate is subjected to treatment by the following process (forexample, treatment in an identical reaction chamber 32, or treatmentusing a vacuum transfer system in other reaction chamber 33 whileavoiding exposure to the air). According to this method, oxidationtreatment can be carried out while optimally maintaining the organiccontaminant removing effect and the spontaneous oxide film removingeffect attained by the treatment in the step (3). More specifically,rare gas and oxygen were allowed to flow respectively 25 to 500 sccmover the silicon and the pressure was held at to 1000 mTorr). Amicrowave to this atmosphere through a at 1000 to 2000 sccm and 50substrate heated at 400° C., 13 Pa to 133 Pa (100 mTorr was applied at 2to 3 W/cm² plane antenna member (RLSA) having a plurality of slots togenerate plasma containing oxygen and rare gas, and this plasma was usedfor the formation of an SiO₂ film on the substrate treated in the step(3) (FIG. 11). Further, the film thickness was regulated by varyingtreatment conditions including treatment time.

(5): Plasma Nitriding Process (FIG. 11)

Nitriding was carried out by the following method on the oxide filmformed in the step (4). While avoiding the exposure of the oxide filmformed in the step (4) to the air, the oxide film is subjected totreatment by the following process (for example, treatment in anidentical reaction chamber 32, or treatment using a vacuum transfersystem in other reaction chamber 33 while avoiding exposure to the air).According to this method, nitriding treatment can be carried out whilesuppressing organic matter contamination and an increase in spontaneousoxide film on the upper part of the oxide film formed in the treatmentin the step (4). More specifically, rare gas and nitrogen were allowedto flow respectively at 500 to 2000 sccm and 4 to 500 sccm over thesilicon substrate heated at 400° C., and the pressure was held at 3 Pato 133 Pa (20 mTorr to 1000 mTorr). A microwave was applied at 3 W/cm²to this atmosphere through a plane antenna member (RLSA) having aplurality of slots to generate plasma containing nitrogen and rare gas,and this plasma was used for the formation of an oxynitride film (SiONfilm) on the substrate (FIG. 11).

(6): Film Thickness Reduction and Recovery of Vfb Shift by HydrogenPlasma (FIG. 11)

Annealing treatment with hydrogen plasma was carried out on theoxynitride film formed in the treatment in the step (5) by the followingmethod. While avoiding the exposure of the oxynitride film formed in thetreatment in the step (5) to the air, the oxynitride film is subjectedto treatment by the following process (for example, treatment in anidentical reaction chamber 32, or treatment using a vacuum transfersystem in other reaction chamber. 33 while avoiding exposure to theair). According to this method, hydrogen plasma annealing treatment canbe carried out while suppressing organic matter contamination and anincrease in spontaneous oxide film on the upper part of the oxynitridefilm formed in the treatment in the step (5). More specifically, raregas and hydrogen were allowed to flow respectively at 500 to 2000 sccmand 4 to 500 sccm over the silicon substrate heated at 400° C., and thepressure was held at 3 Pa to 133 Pa (20 mTorr to 1000 mTorr). Amicrowave was applied at 2 to 3 W/cm² to this atmosphere through a planeantenna member (RLSA) having a plurality of slots to generate plasmacontaining hydrogen and rare gas, and this plasma was used for hydrogenplasma annealing treatment on the oxynitride film (FIG. 11). In FIG. 11,for the SIMS analysis sample, the treatment was stopped in this step,and the analysis was carried out.

(7): Formation of Polysilicon Film for Gate Electrode

A polysilicon film was formed as a gate electrode by CVD on theoxynitride film formed through the treatment in the steps (3) to (6).The silicon substrate with an oxynitride film formed thereon was heatedat 630° C., and silane gas (250 sccm) was supplied under a pressure of33 Pa over the substrate, followed by holding for 30 min to form a 3000A-thick polysilicon film for an electrode on the SiO₂ film.

(8): Doping of P (phosphorus) Into Polysilicon

The silicon substrate prepared in the step (7) was heated to 875° C.,and POCl₃ gas, oxygen and nitrogen were supplied respectively at 350sccm, 200 sccm, and 20000 sccm under the atmospheric pressure over thesubstrate, followed by holding for 24 min. to dope phosphorus into thepolysilicon.

(9): Patterning and Gate Etching

Patterning was carried out by lithography on the silicon substrateprepared in the step (8), and the silicon substrate was then immersed ina liquid chemical of HF:HNO₃:H₂O=1:60:60 for 3 min. to dissolvepolysilicon in its parts remaining unpatterned. Thus, an MOS capacitorwas prepared.

Example 2

The measurement of the MOS capacitor prepared in Example 1 was carriedout by the following methods. The capacitor having a gate electrode areaof 10,000 (m2 was evaluated for CV and IV characteristic. The CVcharacteristic were determined by sweeping the gate voltage from +1 V toabout −3 V at a frequency of 100 kHz and evaluating the capacitance ateach voltage. The electrical film thicknesses and Vfb (flatband voltage)were calculated from the CV characteristic. The IV characteristic weredetermined by sweeping the gate voltage from 0 V to about −5 V andevaluating the value of current which flows at each voltage (leakagecurrent value). The leakage current value at a gate electrode voltageobtained by subtracting −0.4 V from Vfb determined from the CVmeasurement was calculated from the IV characteristic.

FIG. 5 is a diagram showing a comparison of leakage characteristic of anoxide film subjected to previous plasma treatment with leakagecharacteristic of an oxide film not subjected to previous plasmatreatment. In this connection, it should be noted that, for illustratingonly the effect of the previous plasma treatment, the oxide film usedhere have not been subjected to nitriding and post-hydrogen treatment.The electrical film thickness determined from the CV characteristic isplotted as abscissa against leakage current value at a gate voltage Vfb−0.4 V (about −1.2 V because Vfb is about −0.8 V) as ordinate. As can beseen from FIG. 5, the previous plasma treatment could reduce the leakagecurrent value of the oxide film.

FIG. 6 is a diagram showing a comparison of flatband characteristic ofRLSA plasma an oxide film subjected to previous plasma treatment withflatband. characteristic of thermally grown an oxide film currentlycommonly used in devices. The electrical film thickness determined fromthe CV characteristic is plotted as abscissa against flatband voltagedetermined from the CV characteristic as ordinate. It is known that,when defects and the like, which serve as traps of carriers, are presentin the film and interface, the flatband voltage is greatly shifted in anegative direction. However, for the film subjected to previous plasmatreatment, the flatband value was similar to that of the thermally grownoxide film (about −0.8 V), and a deterioration in flatbandcharacteristic in this step was not observed.

FIG. 7 a shows a change in the electrical film thickness of gateoxynitride film using a plurality of steps (multi-process) in thepresent invention with the elapse of time (a change in the electricalfilm thickness for each step). The process time is plotted as abscissaagainst electrical film thickness as ordinate. The electrical filmthickness could be successfully reduced by 1 to 3.5 A by nitriding.Further, a further film thickness reduction could be realized bypost-hydrogen treatment.

FIG. 7 b is a diagram showing a change in flatband voltage of the samefilm as shown in FIG. 9 with the elapse of time (a change in flatbandvoltage for each step). The process time is plotted as abscissa againstflatband voltage as ordinate. It is known that, when detects and thelike, which serve as traps of carriers, are present in the film andinterface, the flatband voltage is greatly shifted in a negativedirection. However, for the film subjected to post-plasma hydrogentreatment, recovery of the flatband shift is observed, indicating thatthe film characteristic deteriorated by nitriding could be recovered.

As can be seen from FIG. 8, upon hydrogen treatment, the film thickness(the thickness of the oxygen-containing layer) is reduced. This isattributable to reduction by a hydrogen reaction species. Control(etching) of a film thickness reduction in a region where the control offilm thickness reduction is difficult (around 10 A) can be realized byeffectively utilizing this step.

As can be seen from FIGS. 7 a and 7 b, according to the presentinvention, a plurality of steps can be successively carried out in areaction chamber under the same principle while avoiding the exposure ofa silicon substrate to the air. For example, a reduction in footprintcan be realized by conducting all steps in a single reaction chamber.Further, also when the individual steps are carried out in respectiveseparate reaction chambers, since reaction chambers identical to eachother in principle of operation are arranged, identical gas piping andoperation panel can be used, leading to the realization of excellentmaintenance and operationality. Further, since identical apparatuses areused, there is no significant fear of cross-contamination between theapparatuses. Even when a cluster construction using a plurality ofreaction chambers is adopted, the processing order can be varied. Gateinsulating film having various characteristic can be prepared by thismethod.

Further, in the above example, the oxynitride film prepared according tothe present invention as such is used as a gate insulating film.Alternatively, a process may be adopted which comprises forming a verythin (about 10 A (angstroms)) oxynitride film according to the presentinvention and forming thereon a film of a material a having highdielectric constant such as a high-k material. According to this method,a stacked gate insulating film structure (gate stack structure) having ahigher level of interfacial characteristic, for example, a higher levelof transistor carrier mobility, than a gate insulating film formed usinga high-k material only.

Example 3

The production process of a logic device in this embodiment is roughlycarried out in the following order: “element isolation R preparation ofMOS transistor R capacitance preparation R formation of interlayerinsulating film and wiring”. Among steps before the preparation of anMOS transistor including the process according to the present invention,particularly the preparation of an MOS structure deeply associated withthe present invention will be explained through a typical example.

(1): Substrate

A P-type or N-type silicon substrate having a specific resistance of 1to 30 Ωcm and plane orientation (100) is used as a substrate. A processfor the preparation of an NHOS transistor using a P-type siliconsubstrate will be explained.

A step of element isolation such as STI or LOCOS and channelimplantation have been carried out on the silicon substrate according tothe purpose, and the surface of the silicon substrate, on which a gateoxide film and a gate insulating film are to be formed, has asacrificial oxide film thereon (FIG. 9).

(2): Cleaning Before Gate Oxide Film (Gate Insulating Film) Formation

In general, the sacrificial oxide film and contamination elements(metals and organic matter, particles) are removed by RCA cleaning usinga combination of APM (a mixed liquid composed of ammonia, aqueoushydrogen peroxide, and pure water) with HPM (a mixed liquid composed ofhydrochloric acid, aqueous hydrogen peroxide, and pure water) and DHF (amixed liquid composed of hydrofluoric acid and pure water). As desired,SPM (a mixed liquid composed of sulfuric acid and aqueous hydrogenperoxide), aqueous ozone, FPM (a mixed liquid composed of hydrofluoricacid, aqueous hydrogen peroxide, and pure water), aqueous hydrochloricacid (a mixed liquid composed of hydrochloric acid and pure water), andorganic alkalis and the like are sometimes used.

(3): Plasma Treatment Before Base Oxidation

After the treatment in the step (2), RLSA plasma treatment is carriedout on the substrate as a step before base oxide film formation.Possible treatment conditions may be, for example, as follows. A waferis transferred to a vacuum (back pressure: not more than 1×10⁻⁴ Pa)reaction chamber 32, and conditions of substrate temperature 400° C.,rare gas (for example, Ar gas) 1000 sccm, and pressure 7 Pa to 133 Pa(50 mTorr to 1000 mTorr) are then held. A microwave is applied at 2 to 3W/cm² to this atmosphere through a plane antenna member (RLSA) having aplurality of slots to generate rare gas plasma for plasma treatment onthe substrate surface. As desired, hydrogen (5 to 30 sccm) may becontained in the mixed gas for hydrogen pre-oxidation plasma treatment(FIG. 10).

(4): Formation of Base Oxide Film

An oxide film is formed by the following method on the silicon substratetreated in the step (3). While avoiding the exposure of the siliconsubstrate treated in the step (3) to the air, the silicon substrate issubjected to treatment by the following process (for example, treatmentin an identical reaction chamber 32). According to this method,oxidation treatment can be carried out while optimally maintaining theorganic contaminant removing effect and the spontaneous oxide filmremoving effect attained by the treatment in the step (3). Morespecifically, rare gas and oxygen are allowed to flow respectively at1000 to 2000 sccm and 50 to 500 sccm over the silicon substrate heatedat 400° C., and the pressure is held at 13 Pa to 133 Pa (100 mTorr to1000 mTorr). A microwave is applied at 2 to 3 W/cm² to this atmospherethrough a plane antenna member (RLSA) having a plurality of slots togenerate plasma containing oxygen and rare gas, and this plasma is usedfor the formation of an SiO₂ film on the substrate treated in the step(3). Further, the film thickness can be regulated by varying treatmentconditions including treatment (process) time (FIG. 11).

(5): Plasma Nitriding Process

Nitriding is carried out by the following method on the oxide filmformed in the step (4). While avoiding the exposure of the oxide filmformed in the step (4) to the air, the oxide film is subjected totreatment by the following process (for example, treatment in anidentical reaction chamber 32, or treatment using a vacuum transfersystem in other reaction chamber 33 while avoiding exposure to the air).According to this method, nitriding treatment can be carried out whilesuppressing organic matter contamination and an increase in spontaneousoxide film on the upper part of the oxide film formed in the treatmentin the step (4). More specifically, rare gas and nitrogen are allowed toflow respectively at 500 to 2000 sccm and 4 to 500 sccm over the siliconsubstrate heated at 400° C., and the pressure is held at 3 Pa to 133 Pa(20 mTorr to 1000 mTorr). A microwave is applied at 2 to 3 W/cm² to thisatmosphere through a plane antenna member (RLSA) having a plurality ofslots to generate plasma containing nitrogen and rare gas, and thisplasma is used for the formation of an oxynitride film (SiON film) onthe substrate (FIG. 11).

(6): Film Thickness Reduction and Recovery of Vfb Shift by HydrogenPlasma

Annealing treatment with hydrogen plasma is carried out on theoxynitride film formed in the treatment in the step (5) by the followingmethod. While avoiding the exposure of the oxynitride film formed in thetreatment in the step (5) to the air, the oxynitride film is subjectedto treatment by the following process (for example, treatment in anidentical reaction chamber 32, or treatment using a vacuum transfersystem in other reaction chamber 33 while avoiding exposure to the air).According to this method, hydrogen plasma annealing treatment can becarried out while suppressing organic matter contamination and anincrease in spontaneous oxide film on the upper part of the oxynitridefilm formed in the treatment in the step (5). More specifically, raregas and hydrogen are allowed to flow respectively at 500 to 2000 sccmand 4 to 500 sccm over the silicon substrate heated at 400° C., and thepressure is held at 3 Pa to 133 Pa (20 mTorr to 1000 mTorr). A microwavewas applied at 2 to 3 W/cm² to this atmosphere through a plane antennamember (RLSA) having a plurality of slots to generate plasma containinghydrogen and rare gas, and this plasma is used for hydrogen plasmaannealing treatment on the oxynitride film (FIG. 11).

(7): Formation of High-k Gate Insulating Film

A film of a high-k material is formed on the base oxynitride film formedin the step (6). Methods for high-k gate insulating film formation areclassified roughly into a process using CVD and a process using PVD.Here the formation of a gate insulating film by CVD will be mainlydescribed. In the formation of a gate insulating film by CVD, rawmaterial gases (for example, HTB: Hf (OC₂H₅)₄ and SiH₄) are suppliedonto the above silicon substrate heated at a temperature falling withinthe range of 200° C. to 1000° C., and thermally produced reactionspecies (for example, Hf radicals, Si radicals, and 0 radicals) areallowed to react with each other on the surface of the film andconsequently to form a film (for example, HfSiO). The reaction speciesare sometimes produced by plasma. The physical film thickness of thegate insulating film may generally be 1 nm to 10 nm (FIG. 12).

(8): Formation of Polysilicon Film for Gate Electrode

A film of polysilicon (including amorphous silicon) is formed, as a gateelectrode for an MOS transistor, by CVD on the high-k gate insulatingfilm (including the base gate oxide film) formed in the step (7). Thesilicon substrate with the gate insulating film formed thereon is heatedto a temperature falling within the range of 500° C. to 650° C., and asilicon-containing gas (for example, silane, disilane, etc.) is suppliedover the substrate under a pressure of 10 to 100 Pa to form a 50 nm to500 nm-thick polysilicon film for an electrode on the gate insulatingfilm. In the gate electrode, silicon germanium and metals (for example,W (tungsten), Ru (ruthenium), TiN (titanium nitride), Ta (tantalum), andMo (molybdenum)) are sometimes used as an alternative to polysilicon(FIG. 13).

Thereafter, patterning of the gate and selective etching are carried outto form an MOS capacitor (FIG. 14), and ion implantation is carried outto form a source and a drain (FIG. 15). Thereafter, annealing is carriedout to activate the dopant (phosphorus (P), arsenic (As), boron (B) orthe like implanted into the channel, the source, and the drain).Subsequently, a step of wiring by combining formation of an interlayerinsulating film, patterning, selective etching, and formation of a metalfilm is carried out as a post-process to prepare an MOS transistorinvolved in this embodiment (FIG. 16). Finally, a step of wiring iscarried out on the. upper part of the transistor in various patterns toprepare a circuit and thus to complete a logic device.

In this Example, a film of Hf silicate (HfSiO film) was formed as theinsulating film. However, an insulating film having other compositionmay also be formed. The gate insulating film may be one or at least twofilm selected from the group consisting of film of conventionallow-dielectric constant SiO₂ and SiON, and relatively high-dielectricconstant SiN, high-dielectric constant Al₂O₃r ZrO₂, HfO₂r and Ta₂O₅called high-k materials, and silicates such as ZrSiO and HfSiO andaluminates such as ZrAlO.

Further, in this Example, the formation of a base gate oxynitride filmis intended. Alternatively, the base gate oxynitride film as such may beused as the gate insulating film without the formation of a film of ahigh-k material. In this case, the thickness of the base oxide filmshould be regulated.

Furthermore, an oxide film not subjected to nitriding may also be usedas the base film, and the oxide film per se may also be used as the gateinsulating film.

Further, as desired, the treatment before oxidation and thepost-hydrogen treatment may also be omitted, and the order of treatmentmay also be changed.

Examples of the order of treatment according to the purposes are asfollows.

1: Formation of Gate Oxide Film

Treatment before oxidation→oxidation treatment→formation of poly film

2: Formation of Gate Oxynitride Film-1

Treatment before oxidation→oxidation treatment→nitriding→post-hydrogentreatment→formation of poly film

3: Formation of Gate Oxynitride Film-2

Treatment before oxidation→nitriding→oxidation treatment→post-hydrogentreatment→formation of poly film

4: Formation of High-k Base Oxide Film

Treatment before oxidation→oxidation treatment→film thickness reductionby post-hydrogen treatment→formation of high-k film→formation of polyfilm

5: Formation of High-k Base Nitride Film

Treatment before nitriding (same as treatment beforeoxidation)→nitriding→post-hydrogen treatment→formation of high-kfilm→formation of poly film

The above embodiments are merely examples of embodiments of the presentinvention. In addition to the above embodiments, other various treatmentmethods can be carried out in an identical apparatus construction.

As described above, according to the present invention, a plurality ofsteps can be successively carried out in a reaction chamber(s) under thesame principle while avoiding the exposure of a silicon substrate to theair. For example, a reduction in footprint can be realized by conductinga plurality of steps of cleaning, oxidation, nitriding, and etching in asingle reaction chamber. Further, also when the individual steps arecarried out in respective separate reaction chambers, since reactionchambers identical to each other in principle of operation are arranged,identical gas piping and operation panel can be used, leading to therealization of excellent maintenance and operationality. Further, sinceidentical apparatuses are used, there is no significant fear ofcross-contamination between the apparatuses. Even when a clusterconstruction using a plurality of reaction chambers is adopted, theprocessing order can be varied. Gate insulating film having variouscharacteristic can be prepared by this method.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, an insulatingfilm having various excellent characteristic (for example, control ofvery small film thickness and a high level of cleanness) can be producedwith a high efficiency (for example, small footprint provided byconducting a plurality of steps of cleaning, oxidation, nitriding, andetching in a single reaction chamber, or simplification ofoperationality and prevention of cross-contamination between apparatusesrealized by conducting various steps in reaction chambers under the sameprinciple of operation).

1. An electronic device including a substrate, manufactured by a processfor forming an insulating film on the surface of the substrate,comprising the steps of: cleaning the substrate with plasma based on acleaning gas comprising a rare gas; oxidizing the substrate with plasmabased on an oxidizing gas comprising a rare gas and oxygen, to therebyform an oxide film thereon; nitriding the oxide film with plasma basedon a nitriding gas comprising a rare gas and nitrogen, to thereby forman oxynitride film thereon; treating the oxynitride film with plasmabased on a treating gas comprising hydrogen after the nitriding torecover defects in the oxynitride film; forming an electrode on theoxynitride film; and, wherein the cleaning and oxidizing are conductedunder the same operation principle; and, the cleaning and oxidizing areconducted in the same vessel without exposure of the substrate to air.2. An electronic device according to claim 1, wherein the substrate issubjected to wet cleaning prior to the cleaning with plasma.
 3. Anelectronic device according to claim 1, wherein the electrode comprisespolysilicon.
 4. An electronic device including a substrate, manufacturedby a process for forming an insulating film on the surface of thesubstrate, comprising the steps of: cleaning the substrate with plasmabased on a cleaning gas comprising a rare gas; oxidizing the substratewith plasma based on an oxidizing gas comprising a rare gas and oxygen,to thereby form an oxide film thereon; treating the oxide film withplasma based on a treating gas comprising hydrogen after the oxidizingto recover defects in the oxide film; forming a High-k film on the oxidefilm after the treating; forming an electrode on the High-k film; and,wherein the cleaning and oxidizing are conducted under the sameoperation principle; and, the cleaning and oxidizing are conducted inthe same vessel without exposure of the substrate to air.
 5. Anelectronic device according to claim 4, wherein the High-k filmcomprises one material selected from the group consisting of Al₂0₃,Zr0₂, Hf0₂, and Ta₂0₅, ZrSiO, HfSiO and ZrA10.
 6. An electronic deviceaccording to claim 4, wherein the process comprises nitriding the oxidefilm with plasma based on a nitriding gas comprising a rare gas andnitrogen after the oxidizing.
 7. An electronic device according to claim4, wherein the electrode comprises one material selected from the groupconsisting of polysilicon, silicon germanium and metal.
 8. An electronicdevice according to claim 4, wherein the treating gas consists of raregas and hydrogen.
 9. An electronic device according to claim 4, whereinthe substrate is subjected to wet cleaning prior to the cleaning withplasma.